Cervical traction equipment has long been used to support the head during treatment and rehabilitation of a neck or spinal injury. In cases where the injury permits patient mobility, it is often desirable to support the head by means of a ring or "halo" which is rigidly affixed to the skull of the patient. The halo is typically supported by means of rods or other connecting members connected to a vest-like apparatus worn on the torso of the patient. There are usually two or four such connecting members, generally spaced symmetrically on either side of the patient's head and attached to the chest and back panels of the vest. In the final adjustment of such equipment, the connecting members are clamped or bolted in the desired positions on the halo so as to exert an upward supporting force on the halo and skull. The counterforce is supplied by the vest, which fits over the shoulders of the patient or, in other cases, may rest on the pelvis.
Making the final adjustments of traditional cervical traction equipment is generally a subjective procedure. The connecting members are bolted to the halo to provide the desired supporting forces based on the collective opinions of the clinician and the patient. The clinician typically will place the patient in a prone position and then pull on the patient's head or straighten the patient's neck while tightening the bolts or other fastening device while inquiring of the patient as to any changes in sensation that are experienced. The subjective responses from the patient are usually major determinants in the final adjustment of the connecting members and bolts and their applied forces.
A major problem with respect to traditional techniques of adjusting known cervical traction equipment is that they lack precision because they depend on the sensations of a patient who is unaccustomed to such equipment. An additional problem with respect to such methods is that cervical injuries are often accompanied by some degree of nerve damage, causing numbness or paralysis; hence, the ability of the patient to report sensatory changes may be limited. Furthermore, the traditional subjective approach to adjusting the supporting force applied to the halo is deficient even in the basic ability to precisely apply balanced supporting forces around the halo and skull since the supporting force of the connecting member can vary from each other.